Add ForeignKeyConstraint to the relational model.

Part of #12846

src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Metadata;
@@ -164,25 +165,29 @@ public static void SetSchema(
         ///     Returns the tables to which the entity type is mapped.
         /// </summary>
         /// <param name="entityType"> The entity type to get the table name for. </param>
-        /// <returns> The name of the table to which the entity type is mapped. </returns>
+        /// <returns> The tables to which the entity type is mapped. </returns>
         public static IEnumerable<ITableMapping> GetTableMappings([NotNull] this IEntityType entityType) =>
-            (IEnumerable<ITableMapping>)entityType[RelationalAnnotationNames.TableMappings];
+            (IEnumerable<ITableMapping>)entityType[RelationalAnnotationNames.TableMappings]
+                ?? Enumerable.Empty<ITableMapping>();
 
         /// <summary>
-        ///     Returns the views or tables to which the entity type is mapped.
+        ///     Returns the views to which the entity type is mapped or the tables of it's not mapped to any views.
         /// </summary>
         /// <param name="entityType"> The entity type to get the table name for. </param>
-        /// <returns> The name of the table to which the entity type is mapped. </returns>
+        /// <returns> The views or tables to which the entity type is mapped. </returns>
         public static IEnumerable<ITableMappingBase> GetViewOrTableMappings([NotNull] this IEntityType entityType) =>
-            (IEnumerable<ITableMappingBase>)GetViewMappings(entityType) ?? GetTableMappings(entityType);
+            (IEnumerable<ITableMappingBase>)(entityType[RelationalAnnotationNames.ViewMappings]
+                ?? entityType[RelationalAnnotationNames.TableMappings])
+                ?? Enumerable.Empty<ITableMappingBase>();
 
         /// <summary>
         ///     Returns the views to which the entity type is mapped.
         /// </summary>
         /// <param name="entityType"> The entity type to get the table name for. </param>
-        /// <returns> The name of the table to which the entity type is mapped. </returns>
+        /// <returns> The views to which the entity type is mapped. </returns>
         public static IEnumerable<IViewMapping> GetViewMappings([NotNull] this IEntityType entityType) =>
-            (IEnumerable<IViewMapping>)entityType[RelationalAnnotationNames.ViewMappings];
+            (IEnumerable<IViewMapping>)entityType[RelationalAnnotationNames.ViewMappings]
+                ?? Enumerable.Empty<IViewMapping>();
 
         /// <summary>
         ///     Returns the name of the view to which the entity type is mapped.

src/EFCore.Relational/Extensions/RelationalForeignKeyExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using JetBrains.Annotations;
@@ -75,5 +76,14 @@ public static void SetConstraintName(
         public static ConfigurationSource? GetConstraintNameConfigurationSource([NotNull] this IConventionForeignKey foreignKey)
             => foreignKey.FindAnnotation(RelationalAnnotationNames.Name)
                 ?.GetConfigurationSource();
+
+        /// <summary>
+        ///     Returns the foreign key constraints to which the foreign key is mapped.
+        /// </summary>
+        /// <param name="foreignKey"> The foreign key. </param>
+        /// <returns> The foreign key constraints to which the foreign key is mapped. </returns>
+        public static IEnumerable<IForeignKeyConstraint> GetConstraintMappings([NotNull] this IForeignKey foreignKey) =>
+            (IEnumerable<IForeignKeyConstraint>)foreignKey[RelationalAnnotationNames.ForeignKeyMappings]
+                ?? Enumerable.Empty<IForeignKeyConstraint>();
     }
 }

src/EFCore.Relational/Extensions/RelationalModelExtensions.cs

@@ -83,8 +83,8 @@ public static ITable FindTable([NotNull] this IModel model, [NotNull] string nam
         /// <summary>
         ///     Returns all the views mapped in the model.
         /// </summary>
-        /// <param name="model"> The model to get the tables for. </param>
-        /// <returns> All the tables mapped in the model. </returns>
+        /// <param name="model"> The model to get the views for. </param>
+        /// <returns> All the views mapped in the model. </returns>
         public static IEnumerable<IView> GetViews([NotNull] this IModel model) =>
             ((IDictionary<(string, string), View>)model[RelationalAnnotationNames.Views])?.Values
                 ?? Enumerable.Empty<IView>();

src/EFCore.Relational/Extensions/RelationalPropertyExtensions.cs

@@ -278,23 +278,27 @@ public static void SetColumnType(
         /// <param name="property"> The property. </param>
         /// <returns> The table columns to which the property is mapped. </returns>
         public static IEnumerable<IColumnMapping> GetTableColumnMappings([NotNull] this IProperty property) =>
-            (IEnumerable<IColumnMapping>)property[RelationalAnnotationNames.TableColumnMappings];
+            (IEnumerable<IColumnMapping>)property[RelationalAnnotationNames.TableColumnMappings]
+                ?? Enumerable.Empty<IColumnMapping>();
 
         /// <summary>
         ///     Returns the view or table columns to which the property is mapped.
         /// </summary>
         /// <param name="property"> The property. </param>
         /// <returns> The view or table columns to which the property is mapped. </returns>
         public static IEnumerable<IColumnMappingBase> GetViewOrTableColumnMappings([NotNull] this IProperty property) =>
-            (IEnumerable<IColumnMappingBase>)GetViewColumnMappings(property) ?? GetTableColumnMappings(property);
+            (IEnumerable<IColumnMappingBase>)(property[RelationalAnnotationNames.ViewColumnMappings]
+                ?? property[RelationalAnnotationNames.TableColumnMappings])
+                ?? Enumerable.Empty<IColumnMappingBase>();
 
         /// <summary>
         ///     Returns the view columns to which the property is mapped.
         /// </summary>
         /// <param name="property"> The property. </param>
         /// <returns> The view columns to which the property is mapped. </returns>
         public static IEnumerable<IViewColumnMapping> GetViewColumnMappings([NotNull] this IProperty property) =>
-            (IEnumerable<IViewColumnMapping>)property[RelationalAnnotationNames.ViewColumnMappings];
+            (IEnumerable<IViewColumnMapping>)property[RelationalAnnotationNames.ViewColumnMappings]
+                ?? Enumerable.Empty<IViewColumnMapping>();
 
         /// <summary>
         ///     Returns the SQL expression that is used as the default value for the column this property is mapped to.

src/EFCore.Relational/Metadata/ICheckConstraint.cs

@@ -14,7 +14,7 @@ public interface ICheckConstraint
         string Name { get; }
 
         /// <summary>
-        ///     The <see cref="IEntityType" /> in which this check constraint is defined.
+        ///     Gets the <see cref="IEntityType" /> in which this check constraint is defined.
         /// </summary>
         IEntityType EntityType { get; }
 

src/EFCore.Relational/Metadata/IColumn.cs

@@ -11,12 +11,12 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IColumn : IColumnBase
     {
         /// <summary>
-        ///     The containing table.
+        ///     Gets the containing table.
         /// </summary>
         new ITable Table { get; }
 
         /// <summary>
-        ///     The property mappings.
+        ///     Gets the property mappings.
         /// </summary>
         new IEnumerable<IColumnMapping> PropertyMappings { get; }
     }

src/EFCore.Relational/Metadata/IColumnBase.cs

@@ -13,27 +13,27 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IColumnBase : IAnnotatable
     {
         /// <summary>
-        ///     The column name.
+        ///     Gets the column name.
         /// </summary>
         string Name { get; }
 
         /// <summary>
-        ///     The column type.
+        ///     Gets the column type.
         /// </summary>
         string Type { get; }
 
         /// <summary>
-        ///     Whether the column can contain NULL.
+        ///     Gets the value indicating whether the column can contain NULL.
         /// </summary>
         bool IsNullable { get; }
 
         /// <summary>
-        ///     The containing table-like object.
+        ///     Gets the containing table-like object.
         /// </summary>
         ITableBase Table { get; }
 
         /// <summary>
-        ///     The property mappings.
+        ///     Gets the property mappings.
         /// </summary>
         IEnumerable<IColumnMappingBase> PropertyMappings { get; }
     }

src/EFCore.Relational/Metadata/IColumnMapping.cs

@@ -9,12 +9,12 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IColumnMapping : IColumnMappingBase
     {
         /// <summary>
-        ///     The target column.
+        ///     Gets the target column.
         /// </summary>
         new IColumn Column { get; }
 
         /// <summary>
-        ///     The containing table mapping.
+        ///     Gets the containing table mapping.
         /// </summary>
         new ITableMapping TableMapping { get; }
     }

src/EFCore.Relational/Metadata/IColumnMappingBase.cs

@@ -12,22 +12,22 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IColumnMappingBase : IAnnotatable
     {
         /// <summary>
-        ///     The mapped property.
+        ///     Gets the mapped property.
         /// </summary>
         IProperty Property { get; }
 
         /// <summary>
-        ///     The target column-like object.
+        ///     Gets the target column-like object.
         /// </summary>
         IColumnBase Column { get; }
 
         /// <summary>
-        ///     The type mapping for the column-like object.
+        ///     Gets the type mapping for the column-like object.
         /// </summary>
         RelationalTypeMapping TypeMapping { get; }
 
         /// <summary>
-        ///     The containing table mapping.
+        ///     Gets the containing table mapping.
         /// </summary>
         ITableMappingBase TableMapping { get; }
     }

src/EFCore.Relational/Metadata/IConventionCheckConstraint.cs

@@ -9,12 +9,12 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IConventionCheckConstraint : ICheckConstraint
     {
         /// <summary>
-        ///     The <see cref="IConventionEntityType" /> in which this check constraint is defined.
+        ///     Gets the <see cref="IConventionEntityType" /> in which this check constraint is defined.
         /// </summary>
         new IConventionEntityType EntityType { get; }
 
         /// <summary>
-        ///     Returns the configuration source for this <see cref="IConventionCheckConstraint" />.
+        ///     Gets the configuration source for this <see cref="IConventionCheckConstraint" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IConventionCheckConstraint" />. </returns>
         ConfigurationSource GetConfigurationSource();

src/EFCore.Relational/Metadata/IConventionDbFunction.cs

@@ -17,17 +17,17 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IConventionDbFunction : IDbFunction
     {
         /// <summary>
-        ///     The <see cref="IConventionModel" /> in which this function is defined.
+        ///     Gets the <see cref="IConventionModel" /> in which this function is defined.
         /// </summary>
         new IConventionModel Model { get; }
 
         /// <summary>
-        ///     The builder that can be used to configure this function.
+        ///     Gets the builder that can be used to configure this function.
         /// </summary>
         IConventionDbFunctionBuilder Builder { get; }
 
         /// <summary>
-        ///     Returns the configuration source for this <see cref="IConventionDbFunction" />.
+        ///     Gets the configuration source for this <see cref="IConventionDbFunction" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IConventionDbFunction" />. </returns>
         ConfigurationSource GetConfigurationSource();
@@ -40,7 +40,7 @@ public interface IConventionDbFunction : IDbFunction
         void SetName([CanBeNull] string name, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="IDbFunction.Name" />.
+        ///     Gets the configuration source for <see cref="IDbFunction.Name" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IDbFunction.Name" />. </returns>
         ConfigurationSource? GetNameConfigurationSource();
@@ -53,7 +53,7 @@ public interface IConventionDbFunction : IDbFunction
         void SetSchema([CanBeNull] string schema, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="IDbFunction.Schema" />.
+        ///     Gets the configuration source for <see cref="IDbFunction.Schema" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IDbFunction.Schema" />. </returns>
         ConfigurationSource? GetSchemaConfigurationSource();
@@ -66,7 +66,7 @@ public interface IConventionDbFunction : IDbFunction
         void SetStoreType([CanBeNull] string storeType, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="IDbFunction.StoreType" />.
+        ///     Gets the configuration source for <see cref="IDbFunction.StoreType" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IDbFunction.StoreType" />. </returns>
         ConfigurationSource? GetStoreTypeConfigurationSource();
@@ -79,7 +79,7 @@ public interface IConventionDbFunction : IDbFunction
         void SetTypeMapping([CanBeNull] RelationalTypeMapping typeMapping, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="IDbFunction.TypeMapping" />.
+        ///     Gets the configuration source for <see cref="IDbFunction.TypeMapping" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IDbFunction.TypeMapping" />. </returns>
         ConfigurationSource? GetTypeMappingConfigurationSource();
@@ -95,13 +95,13 @@ void SetTranslation(
             [CanBeNull] Func<IReadOnlyCollection<SqlExpression>, SqlExpression> translation, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="IDbFunction.Translation" />.
+        ///     Gets the configuration source for <see cref="IDbFunction.Translation" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IDbFunction.Translation" />. </returns>
         ConfigurationSource? GetTranslationConfigurationSource();
 
         /// <summary>
-        ///     The parameters for this function
+        ///     Gets the parameters for this function
         /// </summary>
         new IReadOnlyList<IConventionDbFunctionParameter> Parameters { get; }
     }

src/EFCore.Relational/Metadata/IConventionSequence.cs

@@ -14,7 +14,7 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface IConventionSequence : ISequence
     {
         /// <summary>
-        ///     The <see cref="IConventionModel" /> in which this sequence is defined.
+        ///     Gets the <see cref="IConventionModel" /> in which this sequence is defined.
         /// </summary>
         new IConventionModel Model { get; }
 
@@ -24,7 +24,7 @@ public interface IConventionSequence : ISequence
         IConventionSequenceBuilder Builder { get; }
 
         /// <summary>
-        ///     Returns the configuration source for this <see cref="IConventionSequence" />.
+        ///     Gets the configuration source for this <see cref="IConventionSequence" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="IConventionSequence" />. </returns>
         ConfigurationSource GetConfigurationSource();
@@ -50,7 +50,7 @@ public interface IConventionSequence : ISequence
         void SetIncrementBy(int? incrementBy, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="ISequence.IncrementBy" />.
+        ///     Gets the configuration source for <see cref="ISequence.IncrementBy" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="ISequence.IncrementBy" />. </returns>
         ConfigurationSource? GetIncrementByConfigurationSource();
@@ -76,7 +76,7 @@ public interface IConventionSequence : ISequence
         void SetMaxValue(long? maxValue, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="ISequence.MaxValue" />.
+        ///     Gets the configuration source for <see cref="ISequence.MaxValue" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="ISequence.MaxValue" />. </returns>
         ConfigurationSource? GetMaxValueConfigurationSource();
@@ -89,7 +89,7 @@ public interface IConventionSequence : ISequence
         void SetClrType([CanBeNull] Type clrType, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="ISequence.ClrType" />.
+        ///     Gets the configuration source for <see cref="ISequence.ClrType" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="ISequence.ClrType" />. </returns>
         ConfigurationSource? GetClrTypeConfigurationSource();
@@ -105,7 +105,7 @@ public interface IConventionSequence : ISequence
         void SetIsCyclic(bool? cyclic, bool fromDataAnnotation = false);
 
         /// <summary>
-        ///     Returns the configuration source for <see cref="ISequence.IsCyclic" />.
+        ///     Gets the configuration source for <see cref="ISequence.IsCyclic" />.
         /// </summary>
         /// <returns> The configuration source for <see cref="ISequence.IsCyclic" />. </returns>
         ConfigurationSource? GetIsCyclicConfigurationSource();